A photodiode is a type of photodetector which is capable of converting light into either current or voltage, depending upon the mode of operation. P-N photodiodes are used in applications ranging from photoconductors and charge-coupled devices to use in consumer electronics such as compact disc players, smoke detectors, and the receivers for remote controls.
The material used to make a photodiode is important to defining its properties. This is due mainly to the fact that only photons with sufficient energy to excite electrons across the material's bandgap will produce significant photocurrents. Materials commonly used to produce photodiodes include, for example, silicon, germanium, and indium gallium arsenide.
Photodiodes are manufactured by implanting a dopant (typically n-type) into a substrate to create a p-n junction that senses light. In the manufacturing process, the photodiode implant must be adjusted for each pixel size (i.e., higher dose for smaller pixel sizes), which complicates manufacturing logistics and makes it impossible to run multiple pixel sizes on a single wafer using current technologies. For example, in the manufacturing process, photodiodes of a same pixel size must be manufactured on a single wafer in order to ensure that the correct dosage is implanted into the photodiode. For this reason, photodiodes of different sizes are currently formed on different wafers, since each size photodiode requires a different implant recipe and route for each pixel size.
A significant cost factor in the manufacture of the photodiodes is the design verification phase. This is mainly due to the costs for manufacturing of the mask. For example, as each pixel size has to be formed on a separate wafer, multiple masks have to be manufactured for each wafer. This makes for a very expensive and time consuming process for verifying designs of different pixel sizes, as well as the manufacture of such photodiodes with different pixel sizes.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.